Section 5. Surveillance Systems

4-5-1. Radar

a. Capabilities

1. Radar is a method whereby radio waves are
transmitted into the air and are then received when
they have been reflected by an object in the path of the
beam. Range is determined by measuring the time it
takes (at the speed of light) for the radio wave to go
out to the object and then return to the receiving
antenna. The direction of a detected object from a
radar site is determined by the position of the rotating
antenna when the reflected portion of the radio wave
is received.

2. More reliable maintenance and improved
equipment have reduced radar system failures to a
negligible factor. Most facilities actually have some
components duplicated, one operating and another
which immediately takes over when a malfunction
occurs to the primary component.

b. Limitations

1. It is very important for the aviation
community to recognize the fact that there are
limitations to radar service and that ATC controllers
may not always be able to issue traffic advisories
concerning aircraft which are not under ATC control
and cannot be seen on radar. (See FIG 4-5-1.)

(b) The bending of radar pulses, often called
anomalous propagation or ducting, may cause many
extraneous blips to appear on the radar operator's
display if the beam has been bent toward the ground
or may decrease the detection range if the wave is
bent upward. It is difficult to solve the effects of
anomalous propagation, but using beacon radar and
electronically eliminating stationary and slow
moving targets by a method called moving target
indicator (MTI) usually negate the problem.

(c) Radar energy that strikes dense objects
will be reflected and displayed on the operator's
scope thereby blocking out aircraft at the same range
and greatly weakening or completely eliminating the
display of targets at a greater range. Again, radar
beacon and MTI are very effectively used to combat
ground clutter and weather phenomena, and a method
of circularly polarizing the radar beam will eliminate
some weather returns. A negative characteristic of
MTI is that an aircraft flying a speed that coincides
with the canceling signal of the MTI (tangential or
“blind” speed) may not be displayed to the radar
controller.

(d) Relatively low altitude aircraft will not be
seen if they are screened by mountains or are below
the radar beam due to earth curvature. The only
solution to screening is the installation of strategically placed multiple radars which has been done in
some areas.

(e) There are several other factors which
affect radar control. The amount of reflective surface
of an aircraft will determine the size of the radar
return. Therefore, a small light airplane or a sleek jet
fighter will be more difficult to see on radar than a
large commercial jet or military bomber. Here again,
the use of radar beacon is invaluable if the aircraft is
equipped with an airborne transponder. All ARTCCs'
radars in the conterminous U.S. and many airport
surveillance radars have the capability to interrogate
Mode C and display altitude information to the
controller from appropriately equipped aircraft.
However, there are a number of airport surveillance
radars that don't have Mode C display capability and;
therefore, altitude information must be obtained from
the pilot.

(f) At some locations within the ATC en route
environment, secondary-radar-only (no primary
radar) gap filler radar systems are used to give lower
altitude radar coverage between two larger radar
systems, each of which provides both primary and
secondary radar coverage. In those geographical
areas served by secondary-radar only, aircraft
without transponders cannot be provided with radar
service. Additionally, transponder equipped aircraft
cannot be provided with radar advisories concerning
primary targets and weather.

REFERENCE-
Pilot/Controller Glossary Term- Radar.

(g) The controller's ability to advise a pilot
flying on instruments or in visual conditions of the
aircraft's proximity to another aircraft will be limited
if the unknown aircraft is not observed on radar, if no
flight plan information is available, or if the volume
of traffic and workload prevent issuing traffic
information. The controller's first priority is given to
establishing vertical, lateral, or longitudinal separation between aircraft flying IFR under the control of
ATC.

c. FAA radar units operate continuously at the
locations shown in the Airport/Facility Directory, and
their services are available to all pilots, both civil and
military. Contact the associated FAA control tower or
ARTCC on any frequency guarded for initial
instructions, or in an emergency, any FAA facility for
information on the nearest radar service.

a. The ATCRBS, sometimes referred to as
secondary surveillance radar, consists of three main
components:

1. Interrogator. Primary radar relies on a
signal being transmitted from the radar antenna site
and for this signal to be reflected or “bounced back”
from an object (such as an aircraft). This reflected
signal is then displayed as a “target” on the
controller's radarscope. In the ATCRBS, the
Interrogator, a ground based radar beacon transmitter-receiver, scans in synchronism with the primary
radar and transmits discrete radio signals which
repetitiously request all transponders, on the mode
being used, to reply. The replies received are then
mixed with the primary returns and both are
displayed on the same radarscope.

2. Transponder. This airborne radar beacon
transmitter-receiver automatically receives the signals from the interrogator and selectively replies with
a specific pulse group (code) only to those
interrogations being received on the mode to which
it is set. These replies are independent of, and much
stronger than a primary radar return.

3. Radarscope. The radarscope used by the
controller displays returns from both the primary
radar system and the ATCRBS. These returns, called
targets, are what the controller refers to in the control
and separation of traffic.

b. The job of identifying and maintaining
identification of primary radar targets is a long and
tedious task for the controller. Some of the
advantages of ATCRBS over primary radar are:

1. Reinforcement of radar targets.

2. Rapid target identification.

3. Unique display of selected codes.

c. A part of the ATCRBS ground equipment is the
decoder. This equipment enables a controller to
assign discrete transponder codes to each aircraft
under his/her control. Normally only one code will be
assigned for the entire flight. Assignments are made
by the ARTCC computer on the basis of the National
Beacon Code Allocation Plan. The equipment is also
designed to receive Mode C altitude information
from the aircraft.

NOTE-
Refer to figures with explanatory legends for an illustration
of the target symbology depicted on radar scopes in the
NAS Stage A (en route), the ARTS III (terminal) Systems,
and other nonautomated (broadband) radar systems. (See
FIG 4-5-2 and FIG 4-5-3.)

d. It should be emphasized that aircraft transponders greatly improve the effectiveness of radar
systems.

NOTE-
A number of radar terminals do not have ARTS equipment. Those facilities and certain ARTCCs outside the contiguous U.S.
would have radar displays similar to the lower right hand subset. ARTS facilities and NAS Stage A ARTCCs, when operating
in the nonautomation mode, would also have similar displays and certain services based on automation may not be
available.

EXAMPLE-

1. Areas of precipitation (can be reduced by CP)

2. Arrival/departure tabular list

3. Trackball (control) position symbol (A)

4. Airway (lines are sometimes deleted in part)

5. Radar limit line for control

6. Obstruction (video map)

7. Primary radar returns of obstacles or terrain (can be
removed by MTI)

20. Altitude Mode C readout is 6,000'
(Note: readouts may not be displayed because of
nonreceipt of beacon information, garbled beacon
signals, and flight plan data which is displayed
alternately with the altitude readout)

21. Ground speed readout is 240 knots
(Note: readouts may not be displayed because of a loss
of beacon signal, a controller alert that a pilot was
squawking emergency, radio failure, etc.)

22. Aircraft ID

23. Asterisk indicates a controller entry in Mode C
block. In this case 5,000' is entered and “05” would
alternate with Mode C readout.

24. Indicates heavy

25. “Low ALT” flashes to indicate when an aircraft's
predicted descent places the aircraft in an unsafe
proximity to terrain.
(Note: this feature does not function if the aircraft is not
squawking Mode C. When a helicopter or aircraft is
known to be operating below the lower safe limit, the
“low ALT” can be changed to “inhibit” and flashing
ceases.)

a. Surveillance radars are divided into two general
categories: Airport Surveillance Radar (ASR) and
Air Route Surveillance Radar (ARSR).

1. ASR is designed to provide relatively
short-range coverage in the general vicinity of an
airport and to serve as an expeditious means of
handling terminal area traffic through observation of
precise aircraft locations on a radarscope. The ASR
can also be used as an instrument approach aid.

2. ARSR is a long-range radar system designed
primarily to provide a display of aircraft locations
over large areas.

3. Center Radar Automated Radar Terminal
Systems (ARTS) Processing (CENRAP) was developed to provide an alternative to a nonradar
environment at terminal facilities should an ASR fail
or malfunction. CENRAP sends aircraft radar beacon
target information to the ASR terminal facility
equipped with ARTS. Procedures used for the
separation of aircraft may increase under certain
conditions when a facility is utilizing CENRAP
because radar target information updates at a slower
rate than the normal ASR radar. Radar services for
VFR aircraft are also limited during CENRAP
operations because of the additional workload
required to provide services to IFR aircraft.

b. Surveillance radars scan through 360 degrees of
azimuth and present target information on a radar
display located in a tower or center. This information
is used independently or in conjunction with other
navigational aids in the control of air traffic.

4-5-4. Precision Approach Radar (PAR)

a. PAR is designed for use as a landing aid rather
than an aid for sequencing and spacing aircraft. PAR
equipment may be used as a primary landing aid (See
Chapter 5, Air Traffic Procedures, for additional
information), or it may be used to monitor other types
of approaches. It is designed to display range,
azimuth, and elevation information.

b. Two antennas are used in the PAR array, one
scanning a vertical plane, and the other scanning
horizontally. Since the range is limited to 10 miles,
azimuth to 20 degrees, and elevation to 7 degrees,
only the final approach area is covered. Each scope is
divided into two parts. The upper half presents
altitude and distance information, and the lower half
presents azimuth and distance.

4-5-5. Airport Surface Detection
Equipment - Model X (ASDE-X)

a. The Airport Surface Detection Equipment -
Model X (ASDE-X) is a multi-sensor surface
surveillance system the FAA is acquiring for airports
in the United States. This system will provide high
resolution, short-range, clutter free surveillance
information about aircraft and vehicles, both moving
and fixed, located on or near the surface of the
airport's runways and taxiways under all weather and
visibility conditions. The system consists of:

1. A Primary Radar System. ASDE-X system coverage includes the airport surface and the
airspace up to 200 feet above the surface. Typically
located on the control tower or other strategic
location on the airport, the Primary Radar antenna is
able to detect and display aircraft that are not
equipped with or have malfunctioning transponders.

2. Interfaces. ASDE-X contains an automation interface for flight identification via all
automation platforms and interfaces with the
terminal radar for position information.

3. ASDE-X Automation. A Multi-sensor
Data Processor (MSDP) combines all sensor reports
into a single target which is displayed to the air traffic
controller.

4. Air Traffic Control Tower Display. A high
resolution, color monitor in the control tower cab
provides controllers with a seamless picture of airport
operations on the airport surface.

b. The combination of data collected from the
multiple sensors ensures that the most accurate
information about aircraft location is received in the
tower, thereby increasing surface safety and
efficiency.

c. The following facilities have been projected to
receive ASDE-X:

TBL 4-5-1

STL

Lambert-St. Louis International

CLT

Charlotte Douglas International

SDF

Louisville International Standiford

DFW

Dallas/Ft. Worth International

ORD

Chicago O'Hare International

LAX

Los Angeles International

ATL

Hartsfield Atlanta International

IAD

Washington Dulles International

SEA

Seattle-Tacoma International

MKE

General Mitchell International

MCO

Orlando International

PVD

Theodore Francis Green State

PHX

Phoenix Sky Harbor International

MEM

Memphis International

RDU

Raleigh-Durham International

HOU

William P. Hobby (Houston, TX)

BDL

Bradley International

SJC

San Jose International

SAT

San Antonio International

SMF

Sacramento International

FLL

Ft. Lauderdale/Hollywood

HNL

Honolulu International - Hickam AFB

OAK

Metropolitan Oakland International

IND

Indianapolis International

TPA

Tampa International

BUR

Burbank-Glendale-Pasadena

CMH

Port Columbus International

MDW

Chicago Midway

COS

Colorado Springs Municipal

SNA

John Wayne - Orange County

ONT

Ontario International

AUS

Austin-Bergstrom International

RNO

Reno/Tahoe International

ABQ

Albuquerque International Sunport

SJU

San Juan International

4-5-6. Traffic Information Service (TIS)

a. Introduction

The Traffic Information Service (TIS) provides
information to the cockpit via data link, that is similar
to VFR radar traffic advisories normally received
over voice radio. Among the first FAA-provided data
services, TIS is intended to improve the safety and
efficiency of “see and avoid” flight through an
automatic display that informs the pilot of nearby
traffic and potential conflict situations. This traffic
display is intended to assist the pilot in visual
acquisition of these aircraft. TIS employs an
enhanced capability of the terminal Mode S radar
system, which contains the surveillance data, as well
as the data link required to “uplink” this information
to suitably-equipped aircraft (known as a TIS
“client”). TIS provides estimated position, altitude,
altitude trend, and ground track information for up to
8 intruder aircraft within 7 NM horizontally,
+3,500 and -3,000 feet vertically of the client aircraft
(see FIG 4-5-4, TIS Proximity Coverage Volume).
The range of a target reported at a distance greater
than 7 NM only indicates that this target will be a
threat within 34 seconds and does not display an
precise distance. TIS will alert the pilot to aircraft
(under surveillance of the Mode S radar) that are
estimated to be within 34 seconds of potential
collision, regardless of distance of altitude. TIS
surveillance data is derived from the same radar used
by ATC; this data is uplinked to the client aircraft on
each radar scan (nominally every 5 seconds).

b. Requirements

1. In order to use TIS, the client and any intruder
aircraft must be equipped with the appropriate
cockpit equipment and fly within the radar coverage
of a Mode S radar capable of providing TIS.
Typically, this will be within 55 NM of the sites
depicted in FIG 4-5-5, Terminal Mode S Radar Sites.
ATC communication is not a requirement to receive
TIS, although it may be required by the particular
airspace or flight operations in which TIS is being
used.

NOTE-
Some of the above functions will likely be combined into
single pieces of avionics, such as (a) and (b).

3. To be visible to the TIS client, the intruder
aircraft must, at a minimum, have an operating
transponder (Mode A, C or S). All altitude
information provided by TIS from intruder aircraft is
derived from Mode C reports, if appropriately
equipped.

4. TIS will initially be provided by the terminal
Mode S systems that are paired with ASR-9 digital
primary radars. These systems are in locations with
the greatest traffic densities, thus will provide the
greatest initial benefit. The remaining terminal
Mode S sensors, which are paired with ASR-7 or
ASR-8 analog primary radars, will provide TIS
pending modification or relocation of these sites. See
FIG 4-5-5, Terminal Mode S Radar Sites, for site
locations. There is no mechanism in place, such as
NOTAMs, to provide status update on individual
radar sites since TIS is a nonessential, supplemental
information service.

The FAA also operates en route Mode S radars (not
illustrated) that rotate once every 12 seconds. These
sites will require additional development of TIS
before any possible implementation. There are no
plans to implement TIS in the en route Mode S radars
at the present time.

c. Capabilities

1. TIS provides ground-based surveillance
information over the Mode S data link to properly
equipped client aircraft to aid in visual acquisition of
proximate air traffic. The actual avionics capability of
each installation will vary and the supplemental
handbook material must be consulted prior to using
TIS. A maximum of eight (8) intruder aircraft may be
displayed; if more than eight aircraft match intruder
parameters, the eight “most significant” intruders are
uplinked. These “most significant” intruders are
usually the ones in closest proximity and/or the
greatest threat to the TIS client.

2. TIS, through the Mode S ground sensor,
provides the following data on each intruder aircraft:

(f) Intruder priority as either an “traffic
advisory” or “proximate” intruder.

3. When flying from surveillance coverage of
one Mode S sensor to another, the transfer of TIS is
an automatic function of the avionics system and
requires no action from the pilot.

4. There are a variety of status messages that are
provided by either the airborne system or ground
equipment to alert the pilot of high priority intruders
and data link system status. These messages include
the following:

(a) Alert. Identifies a potential collision
hazard within 34 seconds. This alert may be visual
and/or audible, such as a flashing display symbol or
a headset tone. A target is a threat if the time to the
closest approach in vertical and horizontal coordinates is less than 30 seconds and the closest approach
is expected to be within 500 feet vertically and
0.5 nautical miles laterally.

(b) TIS Traffic. TIS traffic data is displayed.

(c) Coasting. The TIS display is more than
6 seconds old. This indicates a missing uplink from
the ground system. When the TIS display information
is more than 12 seconds old, the “No Traffic” status
will be indicated.

(d) No Traffic. No intruders meet proximate
or alert criteria. This condition may exist when the
TIS system is fully functional or may indicate
“coasting” between 12 and 59 seconds old (see (c)
above).

(e) TIS Unavailable. The pilot has requested TIS, but no ground system is available. This
condition will also be displayed when TIS uplinks are
missing for 60 seconds or more.

(f) TIS Disabled. The pilot has not requested
TIS or has disconnected from TIS.

(g) Good-bye. The client aircraft has flown
outside of TIS coverage.

NOTE-
Depending on the avionics manufacturer implementation,
it is possible that some of these messages will not be directly
available to the pilot.

5. Depending on avionics system design, TIS
may be presented to the pilot in a variety of different
displays, including text and/or graphics. Voice
annunciation may also be used, either alone or in
combination with a visual display. FIG 4-5-6,
Traffic Information Service (TIS), Avionics Block
Diagram,shows an example of a TIS display using
symbology similar to the Traffic Alert and Collision
Avoidance System (TCAS) installed on most
passenger air carrier/commuter aircraft in the U.S.
The small symbol in the center represents the client
aircraft and the display is oriented “track up,” with the
12 o'clock position at the top. The range rings
indicate 2 and 5 NM. Each intruder is depicted by a
symbol positioned at the approximate relative
bearing and range from the client aircraft. The
circular symbol near the center indicates an “alert”
intruder and the diamond symbols indicate “proximate” intruders.

6. The inset in the lower right corner of
FIG 4-5-6, Traffic Information Service (TIS),
Avionics Block Diagram,shows a possible TIS data
block display. The following information is contained in this data block:

(a) The intruder, located approximately
four o'clock, three miles, is a “proximate” aircraft
and currently not a collision threat to the client
aircraft. This is indicated by the diamond symbol
used in this example.

(b) The intruder ground track diverges to the
right of the client aircraft, indicated by the small
arrow.

(c) The intruder altitude is 700 feet less than
or below the client aircraft, indicated by the “-07”
located under the symbol.

(d) The intruder is descending >500 fpm,
indicated by the downward arrow next to the “-07”
relative altitude information. The absence of this
arrow when an altitude tag is present indicates level
flight or a climb/descent rate less than 500 fpm.

NOTE-
If the intruder did not have an operating altitude encoder
(Mode C), the altitude and altitude trend “tags” would
have been omitted.

d. Limitations

1. TIS is NOT intended to be used as a collision
avoidance system and does not relieve the pilot
responsibility to “see and avoid” other aircraft (see
paragraph 5-5-8, See and Avoid). TIS must
not be for avoidance maneuvers during IMC or other
times when there is no visual contact with the intruder
aircraft. TIS is intended only to assist in visual
acquisition of other aircraft in VMC. No recommended avoidance maneuvers are provided for,
nor authorized, as a direct result of a TIS intruder
display or TIS alert.

2. While TIS is a useful aid to visual traffic
avoidance, it has some system limitations that must
be fully understood to ensure proper use. Many of
these limitations are inherent in secondary radar
surveillance. In other words, the information
provided by TIS will be no better than that provided
to ATC. Other limitations and anomalies are
associated with the TIS predictive algorithm.

(a) Intruder Display Limitations. TIS will
only display aircraft with operating transponders
installed. TIS relies on surveillance of the Mode S
radar, which is a “secondary surveillance” radar
similar to the ATCRBS described in paragraph 4-5-2.

(b) TIS Client Altitude Reporting Requirement. Altitude reporting is required by the TIS client
aircraft in order to receive TIS. If the altitude encoder
is inoperative or disabled, TIS will be unavailable, as
TIS requests will not be honored by the ground
system. As such, TIS requires altitude reporting to
determine the Proximity Coverage Volume as
indicated in FIG 4-5-4. TIS users must be alert to
altitude encoder malfunctions, as TIS has no
mechanism to determine if client altitude reporting is
correct. A failure of this nature will cause erroneous
and possibly unpredictable TIS operation. If this
malfunction is suspected, confirmation of altitude
reporting with ATC is suggested.

(c) Intruder Altitude Reporting. Intruders
without altitude reporting capability will be displayed without the accompanying altitude tag.
Additionally, nonaltitude reporting intruders are
assumed to be at the same altitude as the TIS client for
alert computations. This helps to ensure that the pilot
will be alerted to all traffic under radar coverage, but
the actual altitude difference may be substantial.
Therefore, visual acquisition may be difficult in this
instance.

(d) Coverage Limitations. Since TIS is
provided by ground-based, secondary surveillance
radar, it is subject to all limitations of that radar. If an
aircraft is not detected by the radar, it cannot be
displayed on TIS. Examples of these limitations are
as follows:

(1) TIS will typically be provided within
55 NM of the radars depicted in FIG 4-5-5, Terminal
Mode S Radar Sites. This maximum range can vary
by radar site and is always subject to “line of sight”
limitations; the radar and data link signals will be
blocked by obstructions, terrain, and curvature of the
earth.

(2) TIS will be unavailable at low altitudes
in many areas of the country, particularly in
mountainous regions. Also, when flying near the
“floor” of radar coverage in a particular area,
intruders below the client aircraft may not be detected
by TIS.

(3) TIS will be temporarily disrupted when
flying directly over the radar site providing coverage
if no adjacent site assumes the service. A
ground-based radar, like a VOR or NDB, has a zenith
cone, sometimes referred to as the cone of confusion
or cone of silence. This is the area of ambiguity
directly above the station where bearing information
is unreliable. The zenith cone setting for TIS is
34 degrees: Any aircraft above that angle with
respect to the radar horizon will lose TIS coverage
from that radar until it is below this 34 degree angle.
The aircraft may not actually lose service in areas of
multiple radar coverage since an adjacent radar will
provide TIS. If no other TIS-capable radar is
available, the “Good-bye” message will be received
and TIS terminated until coverage is resumed.

(e) Intermittent Operations. TIS operation
may be intermittent during turns or other maneuvering, particularly if the transponder system does not
include antenna diversity (antenna mounted on the
top and bottom of the aircraft). As in (d) above, TIS
is dependent on two-way, “line of sight” communications between the aircraft and the Mode S radar.
Whenever the structure of the client aircraft comes
between the transponder antenna (usually located on
the underside of the aircraft) and the ground-based
radar antenna, the signal may be temporarily
interrupted.

(f) TIS Predictive Algorithm. TIS information is collected one radar scan prior to the scan
during which the uplink occurs. Therefore, the
surveillance information is approximately 5 seconds
old. In order to present the intruders in a “real time”
position, TIS uses a “predictive algorithm” in its
tracking software. This algorithm uses track history
data to extrapolate intruders to their expected
positions consistent with the time of display in the
cockpit. Occasionally, aircraft maneuvering will
cause this algorithm to induce errors in the TIS
display. These errors primarily affect relative bearing
information; intruder distance and altitude will
remain relatively accurate and may be used to assist
in “see and avoid.” Some of the more common
examples of these errors are as follows:

(1) When client or intruder aircraft maneuver excessively or abruptly, the tracking algorithm
will report incorrect horizontal position until the
maneuvering aircraft stabilizes.

(2) When a rapidly closing intruder is on a
course that crosses the client at a shallow angle (either
overtaking or head on) and either aircraft abruptly
changes course within ¼ NM, TIS will display the
intruder on the opposite side of the client than it
actually is.

These are relatively rare occurrences and will be
corrected in a few radar scans once the course has
stabilized.

(g) Heading/Course Reference. Not all TIS
aircraft installations will have onboard heading
reference information. In these installations, aircraft
course reference to the TIS display is provided by the
Mode S radar. The radar only determines ground
track information and has no indication of the client
aircraft heading. In these installations, all intruder
bearing information is referenced to ground track and
does not account for wind correction. Additionally,
since ground-based radar will require several scans
to determine aircraft course following a course
change, a lag in TIS display orientation (intruder
aircraft bearing) will occur. As in (f) above, intruder
distance and altitude are still usable.

(h) Closely-Spaced Intruder Errors. When operating more than 30 NM from the Mode S
sensor, TIS forces any intruder within 3/8 NM of the
TIS client to appear at the same horizontal position as
the client aircraft. Without this feature, TIS could
display intruders in a manner confusing to the pilot in
critical situations (e.g., a closely-spaced intruder that
is actually to the right of the client may appear on the
TIS display to the left). At longer distances from the
radar, TIS cannot accurately determine relative
bearing/distance information on intruder aircraft that
are in close proximity to the client.

Because TIS uses a ground-based, rotating radar for
surveillance information, the accuracy of TIS data is
dependent on the distance from the sensor (radar)
providing the service. This is much the same
phenomenon as experienced with ground-based
navigational aids, such as VOR or NDB. As distance
from the radar increases, the accuracy of surveillance
decreases. Since TIS does not inform the pilot of
distance from the Mode S radar, the pilot must assume
that any intruder appearing at the same position as the
client aircraft may actually be up to 3/8 NM away in
any direction. Consistent with the operation of TIS,
an alert on the display (regardless of distance from the
radar) should stimulate an outside visual scan,
intruder acquisition, and traffic avoidance based on
outside reference.

e. Reports of TIS Malfunctions

1. Users of TIS can render valuable assistance in
the early correction of malfunctions by reporting their
observations of undesirable performance. Reporters
should identify the time of observation, location, type
and identity of aircraft, and describe the condition
observed; the type of transponder processor, and
software in use can also be useful information. Since
TIS performance is monitored by maintenance
personnel rather than ATC, it is suggested that
malfunctions be reported by radio or telephone to the nearest Flight
Service Station (FSS) facility.

1. Automatic Dependent Surveillance-Broadcast (ADS-B) is a surveillance technology being
deployed throughout the NAS (see FIG 4-5-7). The
ADS-B system is composed of aircraft avionics and
a ground infrastructure. Onboard avionics determine
the position of the aircraft by using the GNSS and
transmit its position along with additional information about the aircraft to ground stations for use by
ATC and other ADS-B services. This information is
transmitted at a rate of approximately once per
second.

2. In the United States, ADS-B equipped
aircraft exchange information is on one of two
frequencies: 978 or 1090 MHz. The 1090 MHz
frequency is associated with Mode A, C, and S
transponder operations. 1090 MHz transponders
with integrated ADS-B functionality extend the
transponder message sets with additional ADS-B
information. This additional information is known
as an “extended squitter” message and referred to as
1090ES. ADS-B equipment operating on 978 MHz
is known as the Universal Access Transceiver (UAT).

3. ADS B avionics can have the ability to both
transmit and receive information. The transmission
of ADS-B information from an aircraft is known as
ADS-B Out. The receipt of ADS-B information by
an aircraft is known as ADS-B In. On January 1,
2020, all aircraft operating within the airspace
defined in 14 CFR part 91, § 91.225 will be required
to transmit the information defined in § 91.227
using ADS-B Out avionics.

4. In general, operators flying at 18,000 feet and
above will require equipment which uses 1090 ES.
Those that do not fly above 18,000 may use either
UAT or 1090ES equipment. (Refer to 14 CFR 91.225
and 91.227.) While the regulation will not require it,
operators equipped with ADS-B In will realize
additional benefits from ADS-B broadcast services:
Traffic Information Service – Broadcast (TIS-B)
(paragraph 4-5-8) and Flight Information Service -
Broadcast (FIS-B) (paragraph 4-5-9).

b. ADS-B Certification and Performance
Requirements

ADS-B equipment may be certified as a surveillance
source for air traffic separation services using
ADS-B Out. ADS-B equipment may also be
certified for use with ADS-B In advisory services
that enable appropriately equipped aircraft to
display traffic and flight information. Refer to the
aircraft's flight manual supplement or Pilot
Operating Handbook for the capabilities of a specific
aircraft installation.

c. ADS-B Capabilities
and Procedures

1. ADS-B enables improved surveillance services, both air-to-air and air-to-ground, especially
in areas where radar is ineffective due to terrain or
where it is impractical or cost prohibitive. Initial NAS
applications of air-to-air ADS-B are for “advisory”
use only, enhancing a pilot's visual acquisition of
other nearby equipped aircraft either when airborne
or on the airport surface. Additionally, ADS-B will
enable ATC and fleet operators to monitor aircraft
throughout the available ground station coverage
area.

2. An aircraft's Flight
Identification (FLT ID), also known as registration number or airline flight
number, is transmitted by the ADS­B Out avionics. The FLT ID is comprised of a
maximum of seven alphanumeric characters and also corresponds to the aircraft
identification annotated on the ATC flight plan. The FLT ID for airline and
commuter aircraft is associated with the company name and flight number (for
example, AAL3342). The FLT ID is typically entered by the flightcrew during
preflight through either a Flight Management System (FMS) interface (Control
Display Unit/CDU) or transponder control panel. The FLT ID for General Aviation
(GA) aircraft is associated with the aircraft's registration number. The
aircraft owner can preset the FLT ID to the aircraft's registration number (for
example, N235RA), since it is a fixed value, or the pilot can enter it into the
ADS­B Out system prior to flight.

ATC systems use
transmitted FLT IDs to uniquely identify each aircraft within a given airspace
and correlate them to a filed flight plan for the provision of surveillance and
separation services. If the FLT ID is not entered correctly, ATC automation
systems may not associate surveillance tracks for the aircraft to its filed
flight plan. Therefore, Air Traffic services may be delayed or unavailable until
this is corrected. Consequently, it is imperative that flightcrews and GA pilots
ensure the FLT ID entry correctly matches the aircraft identification annotated
in the filed ATC flight plan.

3. ADS B systems integrated with the transponder will automatically set the applicable emergency
status when 7500, 7600, or 7700 are entered into the
transponder. ADS B systems not integrated with the
transponder, or systems with optional emergency
codes, will require that the appropriate emergency
code is entered through a pilot interface. ADS-B is
intended for in-flight and airport surface use.
ADS-B systems should be turned “on” -- and
remain “on” -- whenever operating in the air and
moving on the airport surface. Civil and military
Mode A/C transponders and ADS-B systems
should be adjusted to the “on” or normal
operating position as soon as practical, unless the
change to “standby” has been accomplished
previously at the request of ATC.

d. ATC Surveillance Services using ADS-B -
Procedures and Recommended Phraseology -
For Use In Alaska Only

Radar procedures, with the exceptions found in this
paragraph, are identical to those procedures prescribed for radar in AIM Chapter 4
and Chapter 5.

1. Preflight:

If a request for ATC services is predicated on ADS-B
and such services are anticipated when either a VFR
or IFR flight plan is filed, the aircraft's “N” number
or call-sign as filed in “Block 2” of the Flight Plan
must be entered in the ADS-B avionics as the
aircraft's flight ID.

2. Inflight:

When requesting ADS-B services while airborne,
pilots should ensure that their ADS-B equipment is
transmitting their aircraft's “N” number or call sign
prior to contacting ATC. To accomplish this, the pilot
must select the ADS-B “broadcast flight ID”
function.

NOTE-
The broadcast “VFR” or “Standby” mode built into some
ADS-B systems will not provide ATC with the appropriate
aircraft identification information. This function should
first be disabled before contacting ATC.

3. Aircraft with an Inoperative/Malfunctioning
ADS-B Transmitter or in the Event of an Inoperative
Ground Broadcast Transceiver (GBT).

(a) ATC will inform the flight crew when the
aircraft's ADS-B transmitter appears to be inoperative or malfunctioning:

1. The ADS-B cockpit display of traffic is NOT
intended to be used as a collision avoidance system
and does not relieve the pilot's responsibility to “see
and avoid” other aircraft. (See paragraph
5-5-8, See and Avoid). ADS-B must not be
used for avoidance maneuvers during IMC or other
times when there is no visual contact with the intruder
aircraft. ADS-B is intended only to assist in visual
acquisition of other aircraft. No avoidance maneuvers are provided nor authorized, as a direct result of
an ADS-B target being displayed in the cockpit.

2. Use of ADS-B radar services is limited to the
service volume of the GBT.

NOTE-
The coverage volume of GBTs are limited to line-of-sight.

f. Reports of ADS-B Malfunctions

Users of ADS-B can provide valuable assistance in
the correction of malfunctions by reporting instances
of undesirable system performance. Reports should
identify the time of observation, location, type and
identity of aircraft, and describe the condition
observed; the type of avionics system and its software
version in use should also be included. Since ADS-B
performance is monitored by maintenance personnel
rather than ATC, it is suggested that malfunctions be
reported in any one of the following ways:

1. By radio or telephone to the nearest Flight
Service Station (FSS) facility.

2. By reporting the failure directly to the FAA
Safe Flight 21 program at 1-877-FLYADSB or
http://www.adsb.gov.

TIS-B is the broadcast of ATC derived traffic
information to ADS-B equipped (1090ES or UAT)
aircraft from ground radio stations. The source of this
traffic information is derived from ground-based air
traffic surveillance radar sensors. TIS-B service
will be available throughout the NAS where there are
both adequate surveillance coverage (radar) from
ground sensors and adequate broadcast coverage
from ADS-B ground radio stations. The quality level
of traffic information provided by TIS-B is
dependent upon the number and type of ground
sensors available as TIS-B sources and the
timeliness of the reported data.

a. TIS-B Requirements.

In order to receive TIS-B service, the following
conditions must exist:

1. Aircraft must be equipped with an ADS-B
transmitter/receiver or transceiver, and a cockpit
display of traffic information (CDTI).

2. Aircraft must fly within the coverage volume
of a compatible ground radio station that is
configured for TIS-B uplinks. (Not all ground radio
stations provide TIS-B due to a lack of radar
coverage or because a radar feed is not available).

3. Aircraft must be within the coverage of and
detected by at least one ATC radar serving the ground
radio station in use.

b. TIS-B Capabilities.

1. TIS-B is intended to provide ADS-B
equipped aircraft with a more complete traffic picture
in situations where not all nearby aircraft are
equipped with ADS-B Out. This advisory-only
application is intended to enhance a pilot's visual
acquisition of other traffic.

2. Only transponder-equipped targets
(i.e., Mode A/C or Mode S transponders) are
transmitted through the ATC ground system
architecture. Current radar siting may result in
limited radar surveillance coverage at lower
altitudes near some airports, with subsequently
limited TIS-B service volume coverage. If there is
no radar coverage in a given area, then there will be
no TIS-B coverage in that area.

c. TIS-B Limitations.

1. TIS-B is NOT intended to be used as a
collision avoidance system and does not relieve the
pilot's responsibility to “see and avoid” other aircraft,
in accordance with 14CFR §91.113b. TIS-B must
not be used for avoidance maneuvers during times
when there is no visual contact with the intruder
aircraft. TIS-B is intended only to assist in the visual
acquisition of other aircraft.

NOTE-
No aircraft avoidance maneuvers are authorized as a
direct result of a TIS-B target being displayed in the
cockpit.

2. While TIS-B is a useful aid to visual traffic
avoidance, its inherent system limitations must be
understood to ensure proper use.

(a) A pilot may receive an intermittent TIS-B
target of themselves, typically when maneuvering
(e.g., climbing turns) due to the radar not tracking
the aircraft as quickly as ADS-B.

(b) The ADS-B-to-radar association process within the ground system may at times have
difficulty correlating an ADS-B report with
corresponding radar returns from the same aircraft.
When this happens the pilot may see duplicate traffic
symbols (i.e., “TIS-B shadows”) on the cockpit
display.

(c) Updates of TIS-B traffic reports will
occur less often than ADS-B traffic updates. TIS-B
position updates will occur approximately once
every 3-13 seconds depending on the type of radar
system in use within the coverage area. In
comparison, the update rate for ADS-B is nominally
once per second.

(d) The TIS-B system only uplinks data
pertaining to transponder-equipped aircraft. Aircraft
without a transponder will not be displayed as TIS-B
traffic.

(e) There is no indication provided when any
aircraft is operating inside or outside the TIS-B
service volume, therefore it is difficult to know if one
is receiving uplinked TIS-B traffic information.

3. Pilots and operators are reminded that the
airborne equipment that displays TIS-B targets is for
pilot situational awareness only and is not approved
as a collision avoidance tool. Unless there is an
imminent emergency requiring immediate action,
any deviation from an air traffic control clearance in
response to perceived converging traffic appearing
on a TIS-B display must be approved by the
controlling ATC facility before commencing the
maneuver, except as permitted under certain
conditions in 14CFR §91.123. Uncoordinated
deviations may place an aircraft in close proximity to
other aircraft under ATC control not seen on the
airborne equipment and may result in a pilot
deviation or other incident.

d. Reports of TIS-B Malfunctions

Users of TIS-B can provide valuable assistance in the
correction of malfunctions by reporting instances of
undesirable system performance. Reporters should
identify the time of observation, location, type and
identity of the aircraft, and describe the condition
observed; the type of avionics system and its software
version used. Since TIS-B performance is monitored
by maintenance personnel rather than ATC, it is
suggested that malfunctions be reported in anyone of
the following ways:

1. By radio or telephone to the nearest Flight
Service Station (FSS) facility.

2. By reporting the failure directly to the FAA
Surveillance and Broadcast Services Program Office
at 1-877-FLYADSB or http://www.adsb.gov.

a. FIS-B is a ground broadcast service provided
through the ADS-B Services network over the
978 MHz UAT data link. The FAA FIS-B system
provides pilots and flight crews of properly equipped
aircraft with a cockpit display of certain aviation
weather and aeronautical information. FIS-B service
availability is expected across the NAS in 2013 and
is currently available within certain regions.

b. The weather products provided by FIS-B are
for information only. Therefore, these products do
not meet the safety and regulatory requirements of
official weather products. The weather products
displayed on FIS-B should not be used as primary
weather products, i.e., aviation weather to meet
operational and safety requirements. Official
weather products (primary products) can be obtained
from a variety of sources including ATC, FSSs, and,
if applicable, AOCC VHF/HF voice, which can
transmit aviation weather, NOTAMS, and other
operational aeronautical information to aircraft in
flight. FIS-B augments the traditional ATC/FSS/AOCC services by providing additional information
and, for some products, offers the advantage of being
displayed graphically. By using FIS-B for orientation
and information, the usefulness of information
received from official sources may be enhanced, but
the user should be alert and understand any
limitations associated with individual products.
FIS-B provides the initial basic products listed below
at no-charge to the user. Additional products are
envisioned, but may incur subscription charges to the
user. FIS-B reception is line-of-sight within the
service volume of the ground infrastructure.

2. Convective Significant Meteorological
Conditions (SIGMET) - Text report/graphical
-Convective SIGMETs (also known internationally
as SIGMET for Convection) are issued for the
contiguous U.S. Each bulletin includes one or more
Convective SIGMETs for a specific region of the
CONUS. Convective SIGMETs issued for thunderstorms and related phenomena do not include
references to all weather associated with thunderstorms such as turbulence, icing, low-level wind
shear and IFR conditions.

4. Special Aviation Reports (SPECI) - Text
reports - Non- routine, unscheduled report when any
of SPECI criteria have been met.Contains all data
elements found in METAR plus additional information which elaborates on data.

5. Next Generation Radar (NEXRAD)
(CONUS and Regional) - Derived from Next
Generation Weather Radar (WSR-88D). Radar
mosaic consists of multiple single site radar images
combined to produce a graphical image on a regional
or national scale. Regional and national radar
mosaics can be found at the National Weather Service
(NWS) Doppler Radar Images web site:
http://radar.weather.gov/ridge/.

REFERENCE-
Advisory Circular AC-00-45, “AviationWeather Services.”

6. Notice to Airmen (NOTAM) Distant and
Flight Data Center (D/FDC) - Text/graphical reports
- includes Temporary Flight Restrictions (TFRs) -
TFR text and graphic reports, prescribes procedures
used to obtain, format, and disseminate information
on unanticipated or temporary changes to components of or hazards in the NAS until the associated
aeronautical charts and related publications have
been amended.

8. Significant Meteorological Information
(SIGMET) - Text/graphical report - Potentially
hazardous en route phenomena such as thunderstorms and hail, turbulence, icing, sand and dust
storms, tropical cyclones, and volcanic ash in an area
affecting 3,000 square miles or an area deemed to
have a significant effect on safety of aircraft
operations.

REFERENCE-
Advisory Circular AC-00-45, “AviationWeather Services.”

9. Special Use Airspace (SUA) Status -
Text/graphical report - Establishes/designates
airspace in the interest of National Defense, security
and/or welfare. Charted SUA identifies to other
airspace users where these activities occur. SUA is
airspace of defined dimensions wherein activities
must be confined because of their nature, or wherein
limitations may be imposed upon aircraft operations
that are not a part of those activities.

10. Terminal Aerodrome Forecast (TAF) and
their amendments (AMEND) - Text report - Routine
forecast that gives a concise statement of expected
meteorological conditions for a specified time period
within five statute miles (SM) of the center of the
airport's runway complex (terminal). TAFs are
amended whenever they become, in the forecaster's
judgment, unrepresentative of existing or expected
conditions, particularly regarding those elements and
events significant to aircraft and airports. An
amended forecast is identified by TAF AMD (in place
of TAF) on the first line of the forecast text.

1 The Update Interval is the rate at which the product data is available from the source.

2 The Transmission Interval is the amount of time within which a new or updated product transmission must be
completed and the rate or repetition interval at which the product is rebroadcast.

NOTE-
Details concerning the content, format, and symbols of the various data link products provided should be obtained from
the specific avionics manufacturer.

4-5-10. Automatic Dependent
Surveillance-Rebroadcast (ADS-R)

ADS-R is a datalink translation function of the ADS-B
ground system required to accommodate the two separate
operating frequencies (978 MHz and 1090 ES). The
ADS-B system receives the ADS-B messages transmitted
on one frequency and ADS-R translates and reformats the
information for rebroadcast and use on the other frequency.
This allows ADS-B In equipped aircraft to see nearby
ADS-B Out traffic regardless of the operating link of the
other aircraft. Aircraft operating on the same ADS-B
frequency exchange information directly and do not
require the ADS-R translation function.